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SubjectRe: [PATCH 2/2] lockdep: check that no locks held at freeze time
On Fri, May 03, 2013 at 02:04:10PM -0700, Colin Cross wrote:
> From: Mandeep Singh Baines <msb@chromium.org>
>
> We shouldn't try_to_freeze if locks are held. Holding a lock can cause a
> deadlock if the lock is later acquired in the suspend or hibernate path
> (e.g. by dpm). Holding a lock can also cause a deadlock in the case of
> cgroup_freezer if a lock is held inside a frozen cgroup that is later
> acquired by a process outside that group.
>
> History:
> This patch was originally applied as 6aa9707099c and reverted in
> dbf520a9d7d4 because NFS was freezing with locks held. It was
> deemed better to keep the bad freeze point in NFS to allow laptops
> to suspend consistently. The previous patch in this series converts
> NFS to call _unsafe versions of the freezable helpers so that
> lockdep doesn't complain about them until a more correct fix
> can be applied.

I don't care about %current change, especially given that it's a debug
interface but that really should be a separate patch, so please split
it out if you want it (and I think we want it).

Thanks.

--
tejun


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